docs: def assert_regex(text, regex, msg_fmt="{msg}"):
      """Fail if text does not match the regular expression.
  
      regex can be either a regular expression string or a compiled regular
      expression object.
  
      >>> assert_regex("Hello World!", r"llo.*rld!$")
      >>> assert_regex("Hello World!", r"\\d")
      Traceback (most recent call last):
          ...
      AssertionError: 'Hello World!' does not match '\\\\d'
  
      The following msg_fmt arguments are supported:
      * msg - the default error message
      * text - text that is matched
      * pattern - regular expression pattern as string
      """
  
      compiled = re.compile(regex)
      if not compiled.search(text):
          msg = "{!r} does not match {!r}".format(text, compiled.pattern)
          fail(msg_fmt.format(msg=msg, text=text, pattern=compiled.pattern))